How to measure wort in kettle?

How do you guys measure your wort while in the brew kettle to know when you have hit your volume or need to top up, etc? First AG on Sat. looking for pointers.

I pre-measured my spoon before brewing my first AG batch. Just add a half gallon of water, mark the spoon with a sharpie, add another half gallon, make another mark, etc... until you get to the top of the pot.

Then when brewing, use the spoon to tell you how much wort you have.

Get yourself a cheapo yardstick from e.g. Home Depot.


Measure the inside diameter of your kettle, in inches. Try to be as accurate as you can on this number.
Calculate the surface area of your vessel. The forumla is:

R = 1/2 * diameter
Pi*R^2

That number also happens to be the number of cubic inches in your kettle, per inch of height.

There are 231 cubic inches in a gallon.

So, the number of inches per gallon (I will call this N) in your kettle is:

N = 231 / (Pi * R^2)

Now, look at the yardstick, and on the back side, mark off with a permanent marker every N inches as a gallon mark. If you want to do half or quarter gallons, that is easy enough...




There is no sense wasting a bunch of water to measure the volume of something that is easy enough to calculate.

LOL yes I was thinking of doing it that way too, but didn't want to do all the math

happypanties said:

I pre-measured my spoon before brewing my first AG batch. Just add a half gallon of water, mark the spoon with a sharpie, add another half gallon, make another mark, etc... until you get to the top of the pot.

Then when brewing, use the spoon to tell you how much wort you have.

Click to expand...

I did the same as above only in 1 gal increments. Etched my paddle with the marks.

weirdboy said:

Get yourself a cheapo yardstick from e.g. Home Depot.


Measure the inside diameter of your kettle, in inches. Try to be as accurate as you can on this number.
Calculate the surface area of your vessel. The forumla is:

R = 1/2 * diameter
Pi*R^2

That number also happens to be the number of cubic inches in your kettle, per inch of height.

There are 231 cubic inches in a gallon.

So, the number of inches per gallon (I will call this N) in your kettle is:

N = 231 / (Pi * R^2)

Now, look at the yardstick, and on the back side, mark off with a permanent marker every N inches as a gallon mark. If you want to do half or quarter gallons, that is easy enough...




There is no sense wasting a bunch of water to measure the volume of something that is easy enough to calculate.

Click to expand...

FYI I didnt waste the water I transferred it to my HLT for the next day brewing. Guess I could have gone the math route as well but I bored and needed to kill some time.

I don't really measure mine anymore. After you get your system dialed in you should have almost exact volumes at the end of the boil every time. After my first few boils I measured the amount left and found that I boil off a gallon every half hour. So I start with 7.5 gallons to have my planned 5.5 gallons.

Every once in a while I measure just to see. And every time I have 5.5 gallons give or take 1/4 gallon tops.

Use a lab thermometer and kill two birds with one stone. Either take measurements from when the thermometer is sitting on the bottom or hanging from the top or both. I can measure my volume to the hundreth of a gallon with ease...not that I need to

I have a notched aluminum "dowel rod" that I have marked in .5 gallon increments.

I use a 4 foot 1 1/4" oak dow rod. I used a wood burning tool to "mark" every 1/2 gal. up to 13 gals.

weirdboy said:

Get yourself a cheapo yardstick from e.g. Home Depot.


Measure the inside diameter of your kettle, in inches. Try to be as accurate as you can on this number.
Calculate the surface area of your vessel. The forumla is:

{snip a bunch of math stuff}

There is no sense wasting a bunch of water to measure the volume of something that is easy enough to calculate.

Click to expand...

We have been down the road a number of times. It is becoming also like the secondary vs. extended primary debate...

You assume the vessel is a perfect cylinder with that formula. Unfortunately, my pot has a rounded edge where the sides meet the bottom, a slight flare which makes the top about a 1/2 wider than the bottom, and a dent in the side, all of which renders the "math solution" not very practical. That is why I used the "fill and mark" method, right before I did my first AG batch. I used my boil kettle to heat my strike water so nothing went to waste.

Math may make things simple in a perfect world, but in reality there are enough variables to make the "fill and mark" method just as easy.

That is one of the things that I love about this hobby. There are so many different ways to do the same thing, alll while making good beer.

No reason to waste the water. Use the below link to figure out gallons per inch and marka ruler...

http://merrycuss.com/calc/kettle_volume.html

Why assume I would waste water? You use your math, and I'll use my eyes.

The rounded bottom is no problem to account for with a hybrid of the math and water methods. You can put in known volumes of water at the beginning and mark the stick up to the point where you're over the rounded edge, then use that math calculation to figure it out the rest of the way. Because above the rounded edge, it is a perfect cylinder (unless you're using a sankey keg or other non-cylindrical pot, of course)

KurtB said:

We have been down the road a number of times. It is becoming also like the secondary vs. extended primary debate...

You assume the vessel is a perfect cylinder with that formula. Unfortunately, my pot has a rounded edge where the sides meet the bottom, a slight flare which makes the top about a 1/2 wider than the bottom, and a dent in the side, all of which renders the "math solution" not very practical. That is why I used the "fill and mark" method, right before I did my first AG batch. I used my boil kettle to heat my strike water so nothing went to waste.

Math may make things simple in a perfect world, but in reality there are enough variables to make the "fill and mark" method just as easy.

Click to expand...

A rounded edge bottom is not very difficult to account for, mathematically speaking. Use the volume of the outer cylinder, and then subtract the volume of a quarter of the torus for that curve at the bottom.

Unless the dent is quite large, you aren't really missing a whole lot of volume by assuming it's cylindrical. Certainly within the measurement error of using "known" quantities of water as a substitute. Also unless the diameter is quite large you probably aren't missing too much by just assuming it's a perfect cylinder, either. Again, within measurement error using other methods, I'd wager.

Many professional brewers come from engineering. I see why...

Why is everyone so excitable about wasting water? I just notched my dowel as I was pouring in strike water. Two birds, one stone, etc.

I measure the first runnings in my heat-resistant 1-gallon measuring cup (from William's Brewing). Once I know the volume of the first runnings, I use a known volume for the sparge. Known sparge volume + first runnings volume = total volume.

Not perfect, but it's worked really well so far. One of these days I'll put a sightglass on my kettle.

40watt said:

Why assume I would waste water? You use your math, and I'll use my eyes.

Click to expand...

Do whatever you want. One is easier and less time consuming than the other.

eobie said:

Do whatever you want. One is easier and less time consuming than the other.

Click to expand...

I would imagine they would take almost the exact same amount of time.

I use a wooden dowel marked with sharpie (would love to have had a wood burning tool), each to their own, some prefer math some prefer other methods. Dowel works for me as I suck at math.

I've got my big nylon brew spoon. I tried marking it with sharpie first, but it wears off quickly (you don't think it went into the beer do you!!). Since then, I scribed marks onto the spoon shaft at 1/2 gal increments. That makes it easy to guess-timate volumes to about 1/4 gal.

The great thing about a stick is that if you put it down in about the middle of the pot and hold the stick approximately vertical, the reading will be pretty much spot on EVERY time no matter if the pot is sitting level.

If you have a sight glass and the pot is not exactly level (or at least in the exact same orientation and angle as when the sight glass was calibrated), you can easily have big volume reading differences. The sight glass location being on the edge of the pot magnifies errors, while measuring near the center of the vessel minimizes errors. For professional brewers with big kettles that never move, sight glasses are great. For homebrewers that move their pot or stand, sight glass measurement might not be so great.

I have a wooden mash paddle that I marked with a sharpie. Poured in one gallon at a time and marked it. Then I used the water to take a bath....



I have 2 different pots so I use both sides:

pabloj13 said:

I would imagine they would take almost the exact same amount of time.

Click to expand...

Only if you add your water one pitcher at a time...

I just stick the hose in my HLT and fill it up until it gets to the right mark.

After reading all this..

I want to calculate the volume of my kettle mathematically, use the fill method, check both methods against each other and dump the water down the drain.

Baldy_Beer_Brewery said:

After reading all this..

I want to calculate the volume of my kettle mathematically, use the fill method, check both methods against each other and dump the water down the drain.

Click to expand...

:fro:

Baldy_Beer_Brewery said:

After reading all this..

I want to calculate the volume of my kettle mathematically, use the fill method, check both methods against each other and dump the water down the drain.

Click to expand...

LOL!

Well the other nice thing about the dow rod method is after a few years the bottom of the rod gets a little jacked up, so you simply cut off "1 gallon" and burn on another gallon at the top. Keep going untill you run out of rod